1. Field of the Invention
This invention relates to improvements in shaft seals of the kind in which at least two sealing rings spaced apart axially from one another act either on a rotating shaft or on a bush fastened to the shaft, the sealing rings preferably being in the form of lip type sealing rings.
2. Description of the Prior Art
For the purpose of cooling lubricants for shaft seals various kinds of devices are known in which an outlet and an inlet for liquid lubricant, for example oil, are provided in radially opposite positions, the outlet and inlet both being connected to a pressure vessel. Through the rotation of the shaft, or of the bush fastened to the shaft, lubricant is forced into the outlet pipe, cooled in the vessel by suitable cooling devices, and the cooled oil is returned into the inlet pipe of the seal.
In a modified arrangement it is also possible, particularly in the case of the so-called stern tube seals for sealing ship's shafts, to provide a special oil pump, which however is relatively expensive. In one known construction of seals of this kind the oil chamber is therefore disposed eccentrically in relation to the shaft, and through the resulting wedge action the oil is guided to a pressure vessel and away from the latter again, the inlet and outlet for the oil being disposed at an angle of about 30.degree. in relation to the shaft axis.
This construction however is comparatively sensitive, and disturbances may occur in the event of the displacement of the shaft. In practice it has been found that, despite such devices, by which a circulation of liquid lubricant is maintained, residues of lubricant are deposited on the sealing rings, so that precisely at these points, which are most exposed to friction, there is an undesirable rise in temperature and therefore premature wear of the sealing rings.
The problem underlying the invention consists in ensuring at low cost, in the case of shaft seals which have at least two sealing rings which are spaced apart axially and between which a quantity of liquid lubricant is disposed, that improved circulation of the lubricant in the chamber of the seal is achieved, particularly in the region of the sealing rings, which are preferably in the form of lip type sealing rings, together with accelerated removal of residues of lubricant and particles of dirt.